Cannot find the 'Manipulate Object Centers Only' button. Is this an addon?
I would post a comment to the above answer, but apparently I need 50 reputation for that so I have to add an answer instead.

The book the OP is referring to is "Blender Foundations: The Essential Guide To Learning Blender 2.6", by Roland Hess. I have this book myself and the text where the author refers to the Manipulate Object Centers Only is in a tutorial where we are trying to box model a simple chair. The effect he wants to achieve is to splay the 4 chair legs out from each other by selecting their bottom faces and using the scale tool:


  However, if you just select the bottom faces of the legs and hit the S
  key, they will move apart as you scale them up, but they will also
  grow in size. We'll try a new pivot style to solve the problem. Beside
  the pivot style menu on the 3D view header is a button called
  Manipulate Object Centers Only. This magical button causes
  transformations to only affect object centers, not their component
  structures. The effect works both in Object mode and Edit mode. In
  this case, selecting the four faces on the bottoms of the legs and
  enabling Manipulate Object Centers Only will move the faces away from
  one another when scaling without actually changing their size.


Note how he mentions the setting works in both Object mode and Edit mode, this seems to imply that we were meant to switch out of Edit mode to Object mode, switch the setting, the come back to Edit mode but he doesn't implicitly tell us this in the book. Having said this,  and after trying it myself this setting doesn't appear to do anything in Edit mode as the above users mention.